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Photosynthesis

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Outline Protist Biology Protist Evolution Protist Diversity Green Algae Red Algae Brown Algae Diatoms Dinoflagellates Protist Diversity, cont. Euglenoids ... – PowerPoint PPT presentation

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Title: Photosynthesis


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Outline
  • Protist Biology
  • Protist Evolution
  • Protist Diversity
  • Green Algae
  • Red Algae
  • Brown Algae
  • Diatoms
  • Dinoflagellates
  • Protist Diversity, cont.
  • Euglenoids
  • Zooflagellates
  • Pseudopods
  • Ciliates
  • Sporozoans
  • Slime Molds
  • Water Molds

3
General Biology of the Protists
  • Classified into the Domain Eukarya the Kingdom
    Protista
  • Morphology
  • Most unicellular
  • Many with amazingly high level of strucrural and
    functional complexity
  • Life cycles
  • Asexual reproduction common
  • Sexual reproduction may occur when conditions
    deteriorate
  • Some life cycles simple, many extremely complex

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Origin of the Eukaryotic Cell
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Ecology of Protists
  • Protists are of enormous eco-logical importance
  • Photoautotrophic forms
  • Produce oxygen
  • Function as producers in both freshwater and
    saltwater ecosystems
  • Major component of plankton
  • Organisms that are suspended in the water
  • Serve as food for heterotrophic protists and
    animals
  • Many protists are symbionts
  • Ranges from strict parasitism to mutualism
  • Coral reefs greatly aided by symbiotic
    photoautotrophic protists in tissues of corals

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Evolution of Protists
  • Complexity and diversity of protists makes them
    difficult to classify
  • Many classification schemes proposed
  • None has broad support
  • Cannot be classified as plants, animals, or fungi
  • Could be split into as many as a dozen kingdoms
  • The scheme chosen for this discussion is based on
    modes of nutrition

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Protist Diversity
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Diversity of ProtistsGreen Algae The
Chlorophyta
  • Phylum Chlorophyta
  • Approximately 7,500 species
  • Inhabit a variety of environments including
    oceans, freshwater, snowbanks, tree bark, and
    turtles backs
  • Many are symbionts with fungi, plants, or animals
  • Morphology varied
  • Majority unicellular, but many are filamentous or
    colonial
  • Some are multicellular and resemble leaves of
    lettuce
  • Plants thought to be derived from Chlorophyta
    because both groups
  • Have a cell wall that contains cellulose
  • Possess chlorophylls a and b, and
  • Store excess food as starch

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Green AlgaeChlamydomonas
  • A minute (lt25 ยต m), actively moving flagellate
  • Inhabits still, freshwater pools
  • Fossil ancestors date back over a billion years
  • Anatomy
  • Definite cell wall
  • Single, large, cup-shaped chloroplast
  • Chloroplast with a pyrenoid where starch is
    synthesized
  • Many with a bright red eyespot, or stigma on
    chloroplast
  • Two long, whip-like flagella
  • Project from the anterior end
  • Operate with a breaststroke motion

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Electron Micrograph of Chlamydomonas
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Green AlgaeChlamydomonas
  • Most often reproduces asexually
  • As many as 16 daughter cells within parent cell
  • Escape by digesting the parent cell
  • Occasionally reproduces sexually
  • Gametes fuse to form a zygote
  • Becomes a heavy-walled, resistant zygospore
  • Goes into a period of dormancy
  • Upon germination produces four zoospores by
    meiosis
  • Spore - a reproductive cell that develops into
    a new organism without fusing with another cell
  • Zoospore - flagellated spores, typical of
    aquatic species

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Reproduction in Chlamydomonas
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Green AlgaeSpirogyra
  • Filamentous green algae
  • Found in green masses on the surfaces of ponds
    and streams
  • Has ribbon-like, spiraled chloroplasts
  • Sexual reproduction by conjugation
  • A temporary union during which the cells exchange
    genetic material
  • Two filaments line up parallel to each other
  • Cell contents of one filament move into the cells
    of the other filament
  • Forms diploid zygospores
  • In spring, undergo meiosis to produce new haploid
    filaments

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Spirogyra
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Green AlgaeMulticellular Forms
  • Ulva
  • Multicellular green alga
  • Commonly called sea lettuce
  • Thallus (body) is two cells thick
  • Can be as much as a meter long
  • Sexual cycle involves alternation of generations
  • Similar to higher plants, except
  • Both generations look exactly alike, and
  • The gametes all look the same

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Multicellular Green Algae
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Green AlgaeColonial Forms
  • Volvox
  • A colony is a loose association of independent
    cells
  • A Volvox colony
  • A hollow sphere
  • Thousands of cells arranged in a single layer
    surrounding a watery interior
  • Each cell of colony resembles a Chlamydomonas
    cell
  • Flagella beat in a coordinated fashion
  • Some cells are specialized for reproduction
  • Each can divide asexually to form a new daughter
    colony within the parental colony
  • Leaves parental colony by releasing an enzyme
    that dissolves away a portion of the parental
    colony

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Volvox
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Diversity of ProtistsRed Algae The Rhodophyta
  • Multicellular
  • About 5,000 species
  • Live mostly in warmer seawater, some as deep as
    200 m
  • Economic Importance
  • Agar - capsules dental impressions cosmetics
    culture medium electrophoresis food prep.
  • Carrageen - an emulsifying agent used in
    chocolate, low-fat foods, cosmetics
  • The reddish-black wrappings around sushi rolls
    consist of processed Porphyra blades

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Red Algae
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Diversity of ProtistsBrown Algae The
Phaeophyta
  • About 1,500 species
  • Most live in colder ocean waters along rocky
    coasts
  • No unicellular or colonial brown forms
  • Morphology
  • Some small forms with simple filaments
  • Others large multicellular forms that may exceed
    200 m in length
  • Pigments
  • Chlorophylls a and c
  • Fucoxanthin (a type of carotinoid pigment) gives
    them their color
  • Excess food stored as a carbohydrate called
    laminarin

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Brown Algae
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The Phaeophyta
  • Multicellular forms of green, red, and brown
    algae are called seaweeds
  • Laminaria (a kelp), and Fucus, (rockweed), are
    common intertidal seaweeds
  • Nereocystis and Macrocystis often form
    forest-like thickets in deeper waters
  • Sargassum forms floating masses where other
    organisms find shelter
  • Harvested for food and fertilizer
  • Macrocystis is source of algin, a thickener for
    foods

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The Phaeophyta
  • Laminaria shows tissue differentiation
  • Transport organic nutrients in a tissue
    resembling phloem
  • Life cycle
  • Most brown algae have alternation of generations
  • In some species of Fucus
  • Meiosis produces gametes instead of spores
  • The adult is always diploid, as in animals

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Diversity of ProtistsYellow-green Algae The
Chrysophyta
  • Diatoms (formerly Bacillariophyta) are the most
    numerous unicellular algae in the oceans
  • Significant portion of phytoplankton
  • Cell wall
  • Two valves, with the larger valve acting as a lid
    (like a mint tin)
  • Contains silica
  • Diatomaceous earth used as
  • Filtering agents
  • Sound-proofing materials
  • Polishing abrasives

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Diversity of ProtistsDinoflagellates The
Pyrrophyta
  • About 4,000 species of unicellular aquatic and
    marine organisms
  • Morphology
  • Cell is usually bounded by protective cellulose
    plates impregnated with silicates
  • Typically with two flagella
  • One in a longitudinal groove with its distal end
    free
  • The other lies in a transverse groove that
    encircles the organism
  • Symbiotic dinoflagellates in corals called
    zooxanthellae
  • Dinoflagellates provide their host with organic
    nutrients
  • Corals provide wastes that fertilize the algae
  • Some lack chloroplasts and are parasitic
  • Gymnodinium brevis may cause red tide
  • Produce a powerful neurotoxin that has caused
    massive fish kills
  • Consume shellfish during outbreak can cause
    respiratory paralysis

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Diatoms and Dinoflagellates
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Fish Kill and Dinoflagellate Bloom
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Diversity of ProtistsThe Euglenoids Phylum
Euglenophyta
  • Small freshwater unicellular organisms
  • Difficult to classify
  • Have two flagella and an eyespot (shades a
    photoreceptor)
  • One flagellum much longer than the other
  • Projects out of an anterior, vase-shaped
    invagination
  • Called a tinsel flagellum because of hair-like
    projections
  • Cell bounded by flexible pellicle
  • Chloroplasts
  • Surrounded by three rather than two membranes
  • With a pyrenoid which produces an unusual type of
    carbohydrate called paramylon

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Euglena
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Diversity of ProtistsZooflagellates Phylum
Zoomastigophora
  • Colorless heterotrophs
  • Most symbiotic and many parasitic
  • Well known for causing various diseases in humans
  • Trypanosoma
  • African sleeping sickness - Tsetse fly
  • Chagas disease Kissing bug
  • Giardia lamblia
  • Most common flagellate in human digestive tract
  • Causes severe diarrhea
  • Cysts are transmitted in contaminated water
  • Beavers are important reservoir hosts
  • Trichomonas vaginalis
  • Sexually transmitted protist,
  • Infects urogenital organs a common cause of
    vaginitis

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Zooflagellates
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Giardia lamblia
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Diversity of ProtistsProtists with Pseudopods
  • Pseudopods form when cytoplasm streams forward in
    a particular direction
  • Amoeboids (phylum Rhizopoda) are protists that
    move and ingest their food with pseudopods
  • Phagocytize food
  • Entamoeba histolytica - a parasite of the human
    colon
  • Causes amoebic dysentery
  • Can be fatal
  • Foraminiferans (phylum Foraminifera) and
    radiolarians (phlyum Actinopoda)
  • Both have a skeleton (test) of either calcite or
    silica

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Protists with Pseudopods
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Diversity of ProtistsThe Ciliates Phylum
Ciliophora
  • Ciliates (phylum Ciliophora) are among the most
    complex of the protozoans
  • Hundreds of cilia beat in coordinated rhythm
  • Most are holozoic, swallowing food whole
  • Divide by transverse binary fission during
    asexual reproduction
  • Two nuclei of differing types
  • Micronucleus Heredity
  • Macronucleus Metabolism

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Ciliates
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Diversity of ProtistsThe Sporozoans Phylum
Apicomplexa
  • Nonmotile obligate parasites
  • Most serious parasitic disease of human is
    malaria
  • Plasmodium spp
  • Kills 3,000,000 people each year
  • Transmitted by mosquito
  • Toxoplasma
  • Humans get from cats
  • Causes birth defects and mental retardation when
    pregnant mom exposed

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Life Cycle of Plasmodium vivax
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Diversity of ProtistsSlime Molds
  • Plasmodial Slime Molds - Phylum Myxomycota
  • Body in the form of a plasmodium
  • Diploid, multinucleated, cytoplasmic mass
  • Enveloped by a slimy sheath
  • Eventually produces sporangium which in turn
    produces spores
  • Cellular Slime Mold - Phylum Acrasiomycota
  • Body in the form of individual amoeboid cells
  • Later aggregate into pseudoplasmodium which then
    forms sporangium spores

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Plasmodial Slime Molds
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Diversity of ProtistsWater Molds - Phylum
Oomycota
  • Most live in the water
  • Phylum name refers to the enlarged tips (called
    oogonia) where eggs are produced
  • Body filamentous, appearing like true Fungi
  • Cell walls largely of cellulose rather than
    chitin
  • The organism is diploid (not haploid as in the
    fungi)
  • Phytophthora infestans caused the 1840s potato
    famine in Ireland
  • Saprolegnia is often seen as a white, cotton-like
    coating on dead aquarium fish

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Water Mold
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Review
  • Protist Biology
  • Protist Evolution
  • Protist Diversity
  • Green Algae
  • Red Algae
  • Brown Algae
  • Diatoms
  • Dinoflagellates
  • Protist Diversity, cont.
  • Euglenoids
  • Zooflagellates
  • Pseudopods
  • Ciliates
  • Sporozoans
  • Slime Molds
  • Water Molds

45
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